The longest living humans on Earth report engaging in daily physical activity as the secret of their longevity. For those who don’t live such long lives, we know that spending too much time being inactive is a major cause of early death. Incredibly, it kills more people in the world than tobacco smoking each year.

Physical inactivity is now sometimes referred to as a “pandemic” – a word normally used to describe diseases such as the plague, which can wipe out a large proportion of a population. At present, few of us are sufficiently active on a daily basis, though the world is slowly waking up to the problem.

The World Health Organisation (WHO) has set a target of reducing the proportion of inactive individuals by 10% by 2025. Yet according to data recently published by the WHO in the Lancet Global Health Journal, we are far from likely to achieve this target. Roughly one third of the world population is still not engaging in enough daily physical activity to remain healthy.

The situation seems worse in rich countries, where twice as many people reported being inactive compared to those in low or middle-income countries (with the exception of Latin America and the Caribbean, where people are also too inactive). In rich countries, the proportion of people who are inactive is also increasing over time. In most other areas of the world, it remains stable.

The authors of the Lancet Global Health article called on affected governments to act urgently to address this problem, by prioritising policies that increase the amount of physical activity that people are doing each day. They referred to increasing cycling and walking infrastructure; improving road safety; and making it easier to take exercise in public spaces, parks and in the workplace. Yet before anyone starts implementing these ideas, there are a couple of major caveats that need taken into account.

Inactivity up close

At face value, the idea that physical inactivity is mainly a “first world” problem makes perfect sense. As countries become richer, people have more spending power and better access to technology. They therefore have less need to be active – whether at work, doing household chores or moving from A to B. Yet this overlooks certain realities about inactivity. In the “first world”, for instance, poorer people are more at risk from physical inactivity and associated diseases such as heart problems, diabetes and certain cancers.

One recent study looked at physical activity in 24 European countries among 51,820 participants. It found that when economic development (GDP per capita) increased in a region, there were also increases in physical activity – but only among higher-educated adults.

So even in Europe, one of the least unequal parts of the world, there are social inequalities in physical activity which are actually increased by economic growth. We suspect that the increasing inactivity in wealthier countries reported by the WHO is related to the fact that the gap between rich and poor in these countries is growing steadily wider.

Neither is wealth the only predictor of physical inactivity. Gender is also very relevant in this context, with women tending to be more inactive than men across the globe. Last year, a Nature article suggested that gender inequality might even be driving the rising global obesity numbers.

It’s not well understood why some groups of people are more inactive than others. It is possible to come up with a tentative answer based on the things that people most often report as being barriers to physical activity: money, time, culture and peer pressure.

At any rate, policies which are blind to these inequalities risk exacerbating them. The problem with the recommendations in the Lancet Global Health paper is who benefits from them. In practice, we know that
policies to encourage people to be more active tend to improve resources in wealthier areas. There’s a big risk of helping the wrong groups of people – further widening the gap in health equality in the process.

Instead, we should be developing policies against inactivity that specifically target those most in need. The question of what this should look like is something that needs more consideration. But as a starting point, policies like improving access to green spaces and adding new cycling and walking infrastructure need to be aimed at those who need them most.

It’s good news that the world’s inactivity problem is at last on the agenda. But unless we get the prescription right, we could be increasing health inequalities and shoring up an even bigger problem for generations to come.